Electric stop mechanism for knitting machines



July 21, 1942. E. vossN 2,290,303

ELECTRIC STOP MECHANISM FOR KNITTING MACHINES Filed July 19, 1940 5 /5r6 INVENTOR. [om/7E0 Vasss/v Patented July 21, 1942 UNET ED Ti it 55 21?it Q 51 i 2,290,303

ELECTREC STQP lJIECI-EANESM FOR KNITTING MACHINES Application July 19,1949, Serial No. 346,273

1 Claim.

This invention relates to automatic electrical stopmechanismsiorknitting machines, commonly called stop motions, and provides a formwhich, in addition to being perfectly. serviceable for knitting withordinary threads of all kinds, is especially adapted to operating withnatural and artificial threads of very light weight which have anexcessive tendency to curl and twist into loops upon the occurrence of aslack. The problem which the invention meets is to construct a stopmotion containing all the best features of such me.:hanism for use withordinary threads, which in addition thereto will set in motion firmly,quickly and precisely a mechanism strong and heavy enough to effectwithout fail in case of need the stoppage of the knitting machine, yetso light in structure and ready and smooth in operation as to minimize,in knitting with Very light threads, breakage from frictional andpressure str .s, and which will also prevent any catching as result ofthe tendency of this class of thread to curl and loop upon theoccurrence of a slack.

In knitting with very light threads where the minimization of pressureand frictional strains on the thread is necessary, there is but onesuitable location for the mechanism, and the triotion arising fromduplication of parts is to be avoided. in consequen great advantage isgained by combining the knot detector, or mech anism for stoppage incase of a knot, with the end detector, or mechanism for stoppage in casean end occurs in the travelling thread.

The drawing and disclosure present a typical form of the device but donot limit the scope of the invention, which covers all forms of itsembodiment.

Fig. 1 shows the device with the side wall of the housing removed todisclose the interior. Fig. 2' shows the same View but with the sidewallin place supporting the tension spring and its adjusting lever. InFig. 3 the device is seen from the reverse side, and Fig. 4 is a topplan View. Fig. 5 shows a breakage in the thread releasing the enddetector lever to move into stopping position. Fig. 6 shows both leversdepressed by thread tension caused by the catching of a knot in thestrainer.

All electrical stop motions are essentially devices to close anelectrical'circuit and energize an-electromagnet to actuate a mechanicaltri which cuts the driving power from the knitting machine, and allowsit to come to a stop. Since the outside circuit, electromagnet and tripare not separately covered by the patent they are merely indicatedwithout description or specific drawing.

The device (Fig. 1) consists of a housing I within which a horizontalpin 2 passes at right angles :from side wall to side wall and serves asa p-ivot'pin for the knot det ctor lever B. The outer arm. of lever 3carries a horizontal crossbar 6 (Fig. 4) from which the two parallelouter portions 5 of knot detector lever 3 extend on either side ofcenter guard 5 and in parallel planes, each outer portion 3 beingforked, with a straight lower tine extending out beyond center guard 5,and an upper tine somewhat shorter and curved downwardly to make withthe lower tine a partially enclosed; space giving full play tothetendency of light threads to curl and twist upon occurrence oi'a slackbut preventing them from fouling the mechanism near the housing. Trisouter portion 6 of lever 3 is ordinarily made of porcelain to minimizethread friction.

Inot detector lever 3 carries onits inner or pivot end a metal piece 7suitably shaped to serve as a contact heel for closing an electricalcircuit with leaf spring 8. Thepivot pin 2 passes through contact piecei about the center thereof leaving a substantial part of the contactpiece to act as inner counterarm olf lever Spiral spring it serves innormal operation to hold heel 1 out of electrical contact with leafspring 8 and the outer arm oflever 3 pressed upwardly against thebackstop extension 9 of housing i. Spring it is attached at its lowerend to the bottom of housing I by a screw permitting regulation of thesprings length and tension and at its upper end to the inner orcounterarm part of contact piece l by means tending to keep the tensionon lever 21 at a minimum at all angles of the latters inclination. Inthe drawing such means of attachment is typified by a ring at the upperend of spring it which, as the angle of inclination of lever 3increases, slides down an extension bar I I attached to the inner orcounterarm part of contact heel l and mininiiizes the elongation ofsping iii increase of its tension caused by the increasing angle. Acontact unit i2 is screwed into but insulated from housing 4 and carriestwo leaf springs, the one spring 3 already referred to serving to makecircuit with contact heel l of the knot detector lever 3 upon depressionof the outer arm thereof, and the other spring l3 serving to makecircuit with contact heel M of the inner counterarm of end detectorlever 55 upon elevation oi the outer arm thereof.

End detector lever l5 (Figs. 1, 3) is pivoted on a .pin I6 fixedthereto, which passes through the housing I at right angles to its sidewalls and turns in the perforations thereof as bearings. Lever I rotatesin a plane parallel to that of knot detector lever 3 and lies whollyoutside of housing I (Fig. 3). The lever i5 is exactly balanced on itspivot it by means of weight I'l' fixed at its inner end so that there isa total absence of gravity actuation.

A spring I 8 attached to the end of a very short crank I9 (Fig. 2)consisting of the upturned end of pivot pin I5 (Fig. 1) serves to holdthe outer arm of lever i5 resting upwardly against the travelling threadin normal operation and move that lever into circuit-closing contactwhen the thread is broken, the contact being made between the contactpiece Id fixed at the inner end of lever I5 and the charged spring I3.By means of a lever Zil pivoted at its lower end to the side wall ofhousing I and fastened at its upper end to spring I8 the tension on thelatter can be regulated. The outer portion of end detector lever I5 ismade of a single wire and is bent or looped around the outer end ofguard 5 and back parallel to itself on the opposite side thereof to apoint within the path of the travelling thread, so that upon occurrenceof a slack in the thread the rise of lever 65 is limited by the loopingof the thread over the lever-arms and under guard 5, and unnecessarystoppage is avoided. Other factors which contribute to prevent theexcessive movement of lever l5 are the weight of the loops and theirfriction, both external and internal.

Guard 5 has, in addition to the foregoing, the primary purpose of aidingto position the travelling thread, the lower edge of guard 5 cooperatingwith knot detector lever arm 6 and end detector lever I5 to form anenclosed space as a path. Guard 5 is usually high in shape with a curvedcontour to its upper edge. This shape not only tends to protect the stopmotion from accidental contacts but also saves the time of the operatorin placing or replacing the thread. The stop motion is ordinarilylocated well above the floor and when the thread has been displaced fromthe stop motion and the knitting machine has come to a stop the operatorcan readily replace the thread by lifting it with a stick to the curvedupper edge of guard 5 and then drawing it down along that edge, thethread engaging and bringing down with it the raised end detector leverI5 and knot detector lever 6 till the thread passes below the end ofguard 5 and is released to slip into normal operative position in theenclosed space made by the lower edge of guard 5 with said levers.

An arm 2i is fixed at its inner end to the lower inner corner of centerguard 5 and extends parallel to th lower edge thereof outwardly from thehousing, in a plane parallel to that of the guard and that of themovement of knot detector lever 3, but closer to the latter than theformer, so that the accumulation of any fuzz in normal operation betweenarm 2I and guard 5 which would obstruct the free vertical play of enddetector lever I5 is prevented. The purpose of arm 2! is to hold thelight travelling thread from curling and twisting off the lever arms incase of a slack, which it tends to do if any width of space is allowedit.

Fig. 1 shows the device in operative position. The travelling thread 22,25 under the drawing force of the knitting needles leaves the spool 23and passes through the eye of the strainer 24 designed to catch anyknot, then passes upward and over the nearer porcelain arm 5 of the knotdetector lever 33, under the fixed arm 2|, over the nearer bight of thelooped wire end detector lever I5, under guard 5, over the farther bightof wire lever I5 and the farther porcelain arm 6 of lever 3 and downward25 to the needles.

Fig. 5 together with Figs. 1 and 2 show the operation of the device whena break in the thread occurs. In normal operation the travelling threadpassing over the outer arm of end detector lever I5 holds it down at thelevel of the knot detector arm 5 against the tension of spring I8 (Fig.2) and thereby holds the contact piece I l at the inner end of lever I5out of electrical contact with leaf spring I3. A break or end in thethread (Fig. 5) releases lever I5 to rise (Fig. 2) under the tension ofspring I8 operating on the upturned end I9 of the pivot wire I 6 as acrank, and the contact heel I4 at the inner end of lever I5 to lowerinto electrical contact with leaf spring I 3. The circuit is closed andthe electromagnet (Fig. 3) is energized to move a trip which cuts thepower from the knitting machine.

Fig. 6 with Fig. 1 shows the operation when a knot occurs in thetravelling thread. As it passes from the spool it catches in the eye ofthe strainer 2 stopping the movement of the thread at this point. Thepull of the knitting needles draws the thread 22, 25 tense from thestrainer over the stop motion and depresses both end detector lever I5and knot detector lever 3, the contact heel 7 on the inner or counterarmof lever B rising into electrical contact with leaf spring 8, closingthe electric circuit, energizing the electromagnet and actuating thetrip to out the power from the knitting machine. The loop of thread thenslips down off of both levers and furnishes slack for the knittingmachine to consume till it comes to rest, thus preventing breakage ofthe thread from tautening between the strainer 2% and the needles.

The device is intended to serve in addition to all ordinary purposes thespecial purpose of knitting with very light threads and it is necessaryto design the actuating forces of the levers to place a minimum strainon the thread. An elastic bed or positioning base is necessary tocushion the strain on the travelling thread, and the por celain arms 6of knot detector lever 3 are utilized to serve this purpose. Thedownward spring tension on counterarm l holding lever 3 up againstbackstop 9 must be sufiicient to provide the necessary steadiness ofbed, but not enough to break the thread, allowing for additional strainsfrom end detector lever I5. The quick even pressure of levers 3 and I5on the thread under spring control is indispensable, and gravityactuation inoperable because under the latter the levers overstrain thethread by bouncing against it owing to the normal vibrations of theknitting machine, the jerky and irregular sticking and detachment of thethread on leaving the spool and the effect of alternately working andidling needles in certain types of knitting.

Since a firm positioning bed for the thread is desirable and thestronger the controlling spring on lever 3 the firmer the bed, as muchas possible of the limited tensile strength of the thread should beemployed to move lever 3 against its spring, and as little as possiblethereof made sufficient to govern lever I5. To attain even pressure andrapid and accurate operation of lever 45 with a minimum of strain on thethread,

that lever is lightly built and exactly counterbalanced on its pivot I6by a counterweight I! (Fig. 3), leaving no gravity actuation to addstrain to the thread.

The use of actuating spring I8 (Fig. 2) with the short crank I9 servestwo purposes (a) of maintaining an even and adjustably minimum tensionon lever I5 at all angles of inclination thereof, and (b) of permittingthe use without excessive tension on lever I5 of a spring I8 as strongas can be properly regulated, exerting sufiicient pressure at the pointof juncture with crank I9 to insure good electrical contact between thetwo notwithstanding deposits of dust and fuzz inescapable in knittingoperations, which deposits would be sufficient to interfere with properelectrical connection between pivot I6 under the light weight of leverI5 and its bearings in housing I. The circuit is therefore led fromlever I5 and its pivot I6 and crank I9 to spring I8, lever 20 andhousing I.

In the foregoing manner all parts are constructed, positioned, andadjusted to provide in knitting with all types of thread smoothoperation with a minimum of frictional and other strains on the thread,and in knitting with very light threads, on occurrence of a knot or enda rapid and precise shifting of levers to close an electric circuit,actuate a trip and cut off the power from the knitting machine.

I claim:

In a stop motion for knitting machines, a housing, a pivot bar extendingtherethrough at right angles to the sides thereof and rotating inapertures in said sides as bearings, a contact heel fixed to said pivotbar interiorly to said housing, a lever fixed to said pivot barexteriorly to said housing and having the end of its exterior arm bentback into a loop, means on the interior counterarm of said lever tocounterbalance the two arms thereof, a crank fixed at one of its ends tosaid pivot bar exteriorly to said housing on the opposite side thereoffrom said lever, a spring governing said lever attached to the free endof said crank and having a path of travel sufficiently long withreference to the length of said crank to equalize spring tension thereonat all angles of rotation of said pivot, means attached to said housingand to said spring to regulate the tension thereof, a second leverpivoted interiorly to said housing and having a plane of rotationparallel to that of the first lever, the exterior arm of said leverbeing vertically bifurcated and each bifurcation vertically forked, aspring governing said lever attached to the interior counterarm thereofand to said housing and holding said lever resiliently in position asbed for the travelling thread, means for regulating the tension of saidspring and equalizing said tension at all angles of inclination of saidlever, a contact heel attached to the interior counterarm of said secondlever, a contact piece attached to but insulated from said housing andcarrying two leaf springs cooperating respectively with the contactheels of said first and second levers, a fiat vertical rigidmember-attached to said housing and extending therefrom in a planeparallel to the planes of rotation of said first and second levers andbetween the two bights of the looped exterior end of said first leverand the bifurcations of said second lever, a second rigid member fixedat its interior end to said first rigid member and extending in a planeparallel thereto and having its lower edge parallel with the lower edgethereof, and lying close to the bifurcation of said second lever whichis first reached by the travelling thread, so that in normal operationthe circuit for carrying the stoppage actuating current is open and thetravelling thread rides over the exterior arms of said first and secondlevers and under said rigid members and within the tines of said secondlever in an enclosed space by said members and levers formed, and onoccurrence of a slack is restrained from escape therefrom by said secondrigid member, but when a break or end occurs in the travelling threadthe first lever rises and its interior heel meets the contact piece andcloses said circuit, and when a knot occurs in the thread a tensionresults therein depressing the second lever and making electric contactwith the interior heel thereof, closing said circuit.

EDWARD VOSSEN.

